1. Field of the Invention
The invention relates to an injection device, more particularly for direct-injection diesel engines.
2. Description of the Related Art
For the injection of fuel into the combustion chamber of a diesel engine, the aim is to draw in highly compressed air out of the combustion chamber by the suction of the diesel injection jet in the narrowest cross section of a spray aperture and to effect introduction into the combustion chamber as a two-phase flow directly at the outlet of the spray aperture or via a diffuser connecting with this spray aperture and having a cylindrical section, so that an explosive mixture is produced continuously during the injection process.
It is known that, in order to achieve an explosive mixture in the diesel engine, high air velocities are desirable which are to be achieved by the momentum exchange between the injection jet and the air and a suitable air control. It has been shown in this connection that it is mainly the jet tip which is involved in the momentum and material exchange and, according to previous studies, an increase in the injection pressure was shown to some extent not in an increase but actually in a reduction of the jet tip velocity. It is known from engine tests that high pressure injection during diesel engine operation leads to reduced NO.sub.x formation. More particularly, no evidence could be found on the basis of previous tests that the injection pressure affects the ignition lag.